So strong is the motive thus prompting the possessor of knowledge to the exclusive retention of his acquisitions, that unless it had been met by another motive appealing in like manner directly to our self-interest, it appears probable that scarcely any general dissemination of knowledge would ever have taken place. The powerful counteracting motive in question is derived from the consideration that in most cases one of the most effective ways which the possessor of knowledge can take of exciting the admiration of others, is to communicate what he knows. The light must give itself forth, and illuminate the world, even that it may be itself seen and admired. In the very darkest times, the scholar or philosopher may find his ambition sufficiently gratified by the mere reputation of superior attainments, and the stupid wonder, or it may be superstitious terror, of the uninquiring multitude. But as soon as any thing like a spirit of intelligence or of curiosity has sprung up in the general mind, all who aspire to fame or consideration from their learning, their discoveries, or their intellectual powers, address themselves to awaken the admiration of their fellow-men, not by concealing, but by displaying their knowledge--not by sealing up the precious fountain, but by allowing its waters to flow freely forth, that all who choose may drink of them. From this time science ceases almost to have any secrets; and, all the influences to which it is exposed acting in the same direction, the tendency of knowledge becomes wholly diffusive.